GM Service Manual Online
For 1990-2009 cars only

Exhaust Muffler Replacement 4.3L, 4.8L, and 5.3L Engines

Removal Procedure


    Object Number: 664840  Size: SH
  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle .
  2. Remove the exhaust muffler nuts.

  3. Object Number: 858600  Size: SH
  4. Apply lubricant to the exhaust insulators in order to aid in removal.
  5. Remove the muffler brackets from the insulators.
  6. Remove the exhaust muffler.

Installation Procedure


    Object Number: 858600  Size: SH
  1. Apply lubricant to the exhaust insulators in order to aid in installation.
  2. Install the muffler to the insulators.

  3. Object Number: 664840  Size: SH

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  4. Install the exhaust muffler nuts.
  5. Tighten
    Tighten the nuts to 40 N·m (30 lb ft).

Exhaust Muffler Replacement 6.0L, 6.6L, and 8.1L Engines

Removal Procedure


    Object Number: 692548  Size: SH
  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle .
  2. Remove the spare tire, if necessary.
  3. Install adjustable jack stands under the rear axle, if necessary.
  4. If equipped with a 8.6 or 9.5 inch ring gear, remove the rear axle vent hose from the rear axle, if necessary.
  5. Remove the vent hose swivel clip from the rear brake crossover pipe, if necessary.

  6. Object Number: 695038  Size: SH
  7. If equipped with a 10.5 inch ring gear, remove the rear axle vent hose from the rear axle, if necessary.
  8. Remove the vent hose swivel clip from the rear brake crossover pipe, if necessary.

  9. Object Number: 665315  Size: SH
  10. Remove the rear shock absorbers lower bolts and nuts, if necessary.
  11. Lower the rear axle using the adjustable jack stands, if necessary.

  12. Object Number: 858609  Size: SH
  13. If equipped with a 6.0L or 8.1L engine, remove the exhaust muffler nuts.
  14. Loosen the exhaust pipe clamp.
  15. With the aid of an assistant, support the exhaust muffler.

  16. Object Number: 1684757  Size: SH
  17. If equipped with a 6.6L engine, loosen the catalytic converter coupling nuts (1).
  18. With the aid of an assistant, support the exhaust muffler.

  19. Object Number: 858603  Size: SH
  20. If equipped with a 6.0L or 8.1L engine, remove the insulators from the frame hangers.
  21. With the aid of an assistant, slide the muffler rearward in order to remove the muffler from the catalytic converter.
  22. Remove the insulators from the muffler hangers.
  23. Remove the exhaust manifold pipe gasket, if necessary.

  24. Object Number: 1684758  Size: SH
  25. If equipped with a 6.6L engine, gently pry up the catalytic converter coupling clip (1) (on the muffler end) in order to disengage the locator button (3) from the coupling clip.
  26. With the aid of an assistant, slide the muffler rearward until the locator button is fully disengaged.

  27. Object Number: 694340  Size: SH
  28. If equipped with a 6.6L engine, remove the insulators from the frame hangers with the aid of an assistant.
  29. Remove the exhaust muffler gasket, if necessary.
  30. Remove the insulators from the muffler hangers.

  31. Object Number: 695550  Size: SH
  32. If equipped with a 6.0L or 8.1L engine, remove the oxygen sensor if the muffler is being replaced.
  33. If the muffler is NOT being replaced as an assembly, the band clamp MUST be replaced. Perform the following:
  34. 25.1. Mark the position of the band clamp on the intermediate exhaust pipe.
    25.2. Remove the band clamp from the exhaust pipe by grinding the weld.
    25.3. Install a NEW band clamp onto the exhaust pipe.

Installation Procedure


    Object Number: 695550  Size: SH
  1. If equipped with a 6.0L or 8.1L engine, and the muffler was replaced re-install the old oxygen sensor.
  2. Apply anti-seize compound GM P/N 12377953 or equivalent to the threads of the old oxygen sensor.
  3. Notice: Refer to Fastener Notice in the Preface section.

  4. Install the oxygen sensor.
  5. Tighten
    Tighten the sensor to 42 N·m (31 lb ft).


    Object Number: 1684758  Size: SH
  6. If equipped with a 6.6L engine, using the aid of an assistant, align the muffler locator button (3) to the catalytic converter coupling groove (2).
  7. Install the muffler until the locator button is fully engaged by the coupling clip (1).

  8. Object Number: 694340  Size: SH

    Important: Apply lubricant to the insulators to aid in installation.

  9. If equipped with a 6.6L engine, install the insulators to the muffler hangers.
  10. Install a new exhaust muffler gasket.
  11. Install the insulators to the frame hangers.

  12. Object Number: 858603  Size: SH

    Important: Apply lubricant to the insulators to aid in installation.

  13. If equipped with a 6.0L or 8.1L engine, install the insulators to the muffler hangers.
  14. Install a new exhaust manifold pipe gasket.
  15. With the aid of an assistant, slide the muffler forward in order to install the muffler to the catalytic converter.
  16. Install the insulators to the frame hangers.

  17. Object Number: 1684757  Size: SH
  18. If equipped with a 6.6L engine, tighten the catalytic converter coupling nuts until snug.
  19. Once snug, tighten the catalytic converter coupling nuts (1) to specifications.
  20. Tighten
    Tighten the nuts to 45 N·m (33 lb ft).


    Object Number: 858609  Size: SH
  21. If equipped with a 6.0L or 8.1L engine, position the NEW band clamp on the intermediate exhaust pipe, using the alignment mark created previously. The band clamp bolt must NOT be positioned below the exhaust pipe.
  22. Install the exhaust muffler nuts.
  23. Tighten the exhaust pipe clamp bolt.
  24. Tighten

        • Tighten the nuts to 40 N·m (30 lb ft).
        • Tighten the clamp to 44 N·m (33 lb ft).

    Object Number: 665315  Size: SH
  25. Raise the rear axle using the adjustable jack stands, if necessary.
  26. Install the rear shock absorbers lower bolts and nuts, if necessary.
  27. Tighten
    Tighten the bolts to 95 N·m (70 lb ft).


    Object Number: 695038  Size: SH
  28. If equipped with a 10.5 inch ring gear, install the rear axle vent hose to the rear axle, if necessary.
  29. Connect the vent hose swivel clip to the rear brake crossover pipe, if necessary.

  30. Object Number: 692548  Size: SH
  31. If equipped with a 8.6 or 9.5 inch ring gear, install the rear axle vent hose to the rear axle, if necessary.
  32. Connect the vent hose swivel clip to the rear brake crossover pipe, if necessary.
  33. Remove the adjustable jack stands from under the rear axle, if necessary.
  34. Install the spare tire, if necessary.
  35. Lower the vehicle.